Expression of differentially expressed nucleolar transforming growth factor-beta1 target (DENTT) in adult mouse tissues

AAV9-Tspyl2 gene therapy retards bleomycin-induced pulmonary fibrosis by modulating downstream TGF-β signaling in mice

Idiopathic pulmonary fibrosis (IPF) is a devastating fibrotic lung disease characterized by scarring and destruction of the lung architecture, with limited treatment options. Targeted gene therapy to restore cell division autoantigen-1 (CDA1) expression may be a potential treatment approach to delay the progression of pulmonary fibrosis (PF). Here, we focused on CDA1, which was significantly decreased in human IPF, in a mouse model of bleomycin (BLM)-induced PF, and in transforming growth factor (TGF-β)-challenged lung fibroblasts. In vitro, CDA1 overexpression by lentivirus infection in human embryonic lung fibroblasts (HFL1 cells) inhibited the production of pro-fibrotic and pro-inflammatory cytokines, lung fibroblast-to-myofibroblast transition, and extracellular matrix protein expression induced by exogenous TGF-β1 treatment, whereas CDA1 knockdown with small interfering RNA promoted this effect. CDA1 overexpression also inhibited cell proliferation and migration. In a mouse model of BLM-induced PF, we provided novel evidence that the intratracheal delivery of adeno-associated virus serotype 9 carrying the mouse Tspyl2 gene reduced lung tissue inflammation and fibrosis. Mechanistically, CDA1, as a transcription regulator, could repress the TGF-β signal transduction in vivo and in vitro. In conclusion, our results show that Tspyl2 gene therapy plays an antifibrotic role by inhibiting the lung fibroblast-to-myofibroblast transition and downstream TGF-β/Smad3 signaling transduction in BLM-induced PF in mice, suggesting that CDA1 is an appropriate and promising therapeutic target for PF.

The X-linked tumor suppressor TSPX downregulates cancer-drivers/oncogenes in prostate cancer in a C-terminal acidic domain dependent manner

TSPX is a tumor suppressor gene located at Xp11.22, a prostate cancer susceptibility locus. It is ubiquitously expressed in most tissues but frequently downregulated in various cancers, including lung, brain, liver and prostate cancers. The C-terminal acidic domain (CAD) of TSPX is crucial for the tumor suppressor functions, such as inhibition of cyclin B/CDK1 phosphorylation and androgen receptor transactivation. Currently, the exact role of the TSPX CAD in transcriptional regulation of downstream genes is still uncertain. Using different variants of TSPX, we showed that overexpression of either TSPX, that harbors a CAD, or a CAD-truncated variant (TSPX[∆C]) drastically retarded cell proliferation in a prostate cancer cell line LNCaP, but cell death was induced only by overexpression of TSPX. Transcriptome analyses showed that TSPX or TSPX[∆C] overexpression downregulated multiple cancer-drivers/oncogenes, including MYC and MYB, in a CAD-dependent manner and upregulated various tumor suppressors in a CAD-independent manner. Datamining of transcriptomes of prostate cancer specimens in the Cancer Genome Atlas (TCGA) dataset confirmed the negative correlation between the expression level of TSPX and those of MYC and MYB in clinical prostate cancer, thereby supporting the hypothesis that the CAD of TSPX plays an important role in suppression of cancer-drivers/oncogenes in prostatic oncogenesis.

Expression of the human TSPY gene in the brains of transgenic mice suggests a potential role of this Y chromosome gene in neural functions

The testis specific protein Y-encoded (TSPY) is a member of TSPY/SET/NAP1 superfamily, encoded within the gonadoblastoma locus on the Y chromosome. TSPY shares a highly conserved SET/NAP-domain responsible for protein--protein interaction among TSPY/SET/NAP1 proteins. Accumulating data, so far, support the role of TSPY as the gonadoblastoma gene, involved in germ cell tumorigenesis. The X-chromosome homolog of TSPY, TSPX is expressed in various tissues at both fetal and adult stages, including the brain, and is capable of interacting with the multi-domain adapter protein CASK, thereby influencing the synaptic and transcriptional functions and developmental regulation of CASK in the brain and other neural tissues. Similar to TSPX, we demonstrated that TSPY could interact with CASK at its SET/NAP-domain in cultured cells. Transgenic mice harboring a human TSPY gene and flanking sequences showed specific expression of the human TSPY transgene in both testis and brain. The neural expression pattern of the human TSPY gene overlapped with those of the endogenous mouse Cask and Tspx gene. Similarly with TSPX, TSPY was co-localized with CASK in neuronal axon fibers in the brain, suggesting a potential role(s) of TSPY in development and/or physiology of the nervous system.

Role of Cell Division Autoantigen 1 (CDA1) in Cell Proliferation and Fibrosis

Cell Division Autoantigen 1 (CDA1) was discovered following screening a human expression library with serum from a patient with Discoid Lupus Erythematosus. CDA1, encoded by TSPYL2 on the X chromosome, shares anti-proliferative, pro‑fibrotic properties with TGF-β. It inhibits cell growth through p53, pERK1/2, p21‑mediated pathways, is implicated in tumorigenesis, the DNA damage response. Its pro-fibrotic property is mediated through cross-talk with TGF-β that results in upregulation of extracellular matrix proteins. The latter properties have identified a key role for CDA1 in diabetes associated atherosclerosis. These dual properties place CDA1 as an attractive molecular target for treating tumors, vascular fibrosis including atherosclerosis, other vascular disorders associated with enhanced TGF-β action, tissue scarring.

Cell division autoantigen 1 plays a profibrotic role by modulating downstream signalling of TGF-beta in a murine diabetic model of atherosclerosis

AIMS/HYPOTHESIS

Excess accumulation of vascular extracellular matrix (ECM) is an important pathological process in cardiovascular diseases including diabetes-associated atherosclerosis. We explored how a recently identified molecule, cell division autoantigen 1 (CDA1), influences the profibrotic TGF-beta pathway leading to vascular ECM accumulation.

METHODS

Expression levels of genes encoding for CDA1, TGF-beta and connective tissue growth factor (CTGF) were examined in aorta from Apoe(-/-) mice with or without diabetes. We used retroviral and adenoviral constructs to knockdown or overexpress Tspyl2, the gene encoding CDA1, in mouse vascular smooth muscle cells (VSMCs) with or without TGF-beta treatment in order to demonstrate the role of CDA1 in TGF-beta signalling.

RESULTS

In vivo studies indicated that the mRNA levels of CDA1-encoding gene Tspyl2 and protein levels of CDA1 were elevated in the aorta of diabetic Apoe(-/-) mice, accompanied by increased levels of Tgf-beta (also known as Tgfb1), Ctgf and ECM accumulation. In vitro studies in vascular cells showed that TGF-beta treatment rapidly increased CDA1 protein levels, which then amplified TGF-beta signalling leading to upregulation of ECM genes. Knockdown of CDA1-encoding gene Tspyl2 to reduce cellular CDA1 level markedly attenuated TGF-beta-stimulated MAD homologue 3 (drosophila; SMAD3) phosphorylation and transcriptional activities. CDA1 overproduction increased and Tspyl2 knockdown decreased expression of TGF-beta receptor type I, TbetarI (also known as Tgfbr1), but not TGF-beta receptor type II, TbetarII (also known as Tgfbr2), providing a mechanism for CDA1's action in modulating TGF-beta signalling. Knockdown of CDA1-encoding gene Tspyl2 also blocked the profibrotic effect of TGF-beta in VSMCs.

CONCLUSIONS/INTERPRETATION

CDA1 plays an important role in vascular ECM accumulation by amplifying TGF-beta signalling. This is critical for the profibrotic effect of TGF-beta in the vasculature. CDA1 is therefore a potential target for attenuating vascular ECM accumulation caused by enhanced TGF-beta action, as seen in diabetic atherosclerosis.

Gonadoblastoma locus and the TSPY gene on the human Y chromosome

The gonadoblastoma (GBY) locus is the only oncogenic locus on the human Y chromosome. It is postulated to serve a normal function in the testis, but could exert oncogenic effects in dysgenetic gonads of individuals with intersex and/or dysfunctional testicular phenotypes. Recent studies establish the testis-specific protein Y-encoded (TSPY) gene to be the putative gene for GBY. TSPY serves normal functions in male stem germ cell proliferation and differentiation, but is ectopically expressed in early and late stages of gonadoblastomas, testicular carcinoma in situ (the premalignant precursor for all testicular germ cell tumors), seminomas, and selected nonseminomas. Aberrant TSPY expression stimulates protein synthetic activities, accelerates cell proliferation, and promotes tumorigenicity in athymic mice. TSPY binds to type B cyclins, enhances an activated cyclin B-CDK1 kinase activity, and propels a rapid G(2)/M transition in the cell cycle. TSPY also counteracts the normal functions of its X-homologue, TSPX, which also binds to cyclin B and modulates the cyclin B-CDK1 activity to insure a proper G(2)/M transition in the cell cycle. Hence, ectopic expression and actions of the Y-located TSPY gene in incompatible germ cells, such as those in dysgenetic or ovarian environments and dysfunctional testis, disrupt the normal cell cycle regulation and predispose the host cells to tumorigenesis. The contrasting properties of TSPY and TSPX suggest that somatic cancers, such as intracranial germ cell tumors, melanoma, and hepatocellular carcinoma, with detectable TSPY expression could exhibit sexual dimorphisms in the initiation and/or progression of the respective oncogenesis.

Differentially expressed nucleolar transforming growth factor-beta1 target (DENTT) exhibits an inhibitory role on tumorigenesis

Differentially expressed nucleolar transforming growth factor-beta1 target (DENTT), also known as testis-specific protein Y-encoded-like (TSPYL-2) and cell division autoantigen-1, is a member of the testis-specific protein Y-encoded (TSPY)/TSPY-L/SET/nucleosome assembly protein-1 superfamily. DENTT is expressed in various tissues including normal human lung. Here, we investigate the involvement of DENTT in cancer promotion and progression. DENTT messenger RNA (mRNA) and protein levels were shown to be markedly downregulated in human and mouse primary tumors and in human tumor cell lines. Overexpression of DENTT in human lung (A549-DENTT) and breast (MCF-7-DENTT) cancer cells resulted in diminished growth potential in anchorage-dependent growth assays and reduced capacity to form colonies under anchorage-independent culture conditions. The migratory potential of A549-DENTT and MCF-7-DENTT cells was reduced when compared with empty vector control cells. Treating human lung cell lines with demethylating agents increased DENTT expression significantly. DENTT expression pattern paralleled that of transforming growth factor-beta1 (TGF-beta1) in normal and malignant tissue and ectopic expression or treatment with TGF-beta1 in lung cancer cells was followed by increased DENTT mRNA and protein levels. Collectively, our results suggest a role for DENTT as a suppressor of the tumorigenic phenotype.

Antiproliferative autoantigen CDA1 transcriptionally up-regulates p21(Waf1/Cip1) by activating p53 and MEK/ERK1/2 MAPK pathways

We previously reported that overexpression of cell division autoantigen 1 (CDA1) in HeLa cells arrests cell growth and inhibits DNA synthesis at S-phase. Here we show that CDA1-induced arrest of cell growth is accompanied by increases in protein and mRNA levels of the cyclin-dependent kinase (Cdk) inhibitor protein, p21(Waf1/Cip1) (p21). Both p21 induction and cell growth arrest are reversed when CDA1 expression is inhibited. CDA1 also increases p53 protein, but not its mRNA, in a time- and dose-dependent manner. MDM2, a ubiquitin ligase regulating p53 degradation, is inactivated by CDA1, suggesting that p53 protein accumulation is due to decreased protein degradation. Knockdown of p53, using siRNA targeting two sites of p53 mRNA, abrogates transcriptional induction of p21 by CDA1. Deletion of the p53 responsive element in the distal region of p21 promoter attenuates promoter activity in response to CDA1. DNA damage caused by camptothecin treatment increases mRNA and protein levels of CDA1, accompanied by induction of p53. The DNA damage-induced p53 induction is markedly attenuated by CDA1 knockdown. CDA1 induces phosphorylation of ERK1/2(p44/42), an activity blocked by PD98059 and U0126, inhibitors of the upstream kinase MEK1/2. The MEK inhibitors also block induction of p21 mRNA and abrogate p21 promoter activity stimulated by CDA1. Cell cycle kinases, Cdk1, -2, -4, and -6 are inhibited by CDA1 overexpression. We conclude that CDA1 induces p53- and MEK/ERK1/2 MAPK-dependent expression of p21 by acting through the p53 responsive element in the p21 promoter and that this contributes to its antiproliferative activity.

Differentially expressed nucleolar TGF-beta1 target (DENTT) shows tissue-specific nuclear and cytoplasmic localization and increases TGF-beta1-responsive transcription in primates

Differentially Expressed Nucleolar TGF-beta1 Target (DENTT) is a new member of the TSPY/TSPY-like/SET/NAP-1 (TTSN) superfamily whose mRNA is induced by TGF-beta1 in TGF-beta1-responsive human lung cancer cells. Monkey DENTT mRNA contains a 2085-bp open reading frame that encodes a predicted polypeptide of 695 amino acids with five nuclear localization signals, two coiled-coil regions, and a domain that shows significant identity to a region that defines the TTSN superfamily. RT-PCR amplification and Western blot analyses showed DENTT mRNA and protein in adult monkey tissues, including the adrenal gland, cerebral cortex, and ovary. Immunohistochemical staining showed that numerous neurons were intensely immunoreactive for DENTT, as were anterior pituitary secretory cells, thyroid follicular cells, and smooth muscle cells of arteries and lung bronchial walls. DENTT expression was also prominent in monkey bronchiolar-alveolar adenomas and cell lines. While the addition of TGF-beta1 or retinoic acid to monkey normal lung bronchial 12MBr6 cells and human lung cancer NCI-H727 cells increased DENTT protein production, TGF-beta1 together with retinoic acid resulted in a more sustained increase in DENTT production than with TGF-beta1 or retinoic acid alone. Transient transfection studies showed that ectopic DENTT expression significantly increased TGF-beta1-responsive 3TP-Lux and CAGA12-Lux reporter transcription in 12MBr6 and NCI-H727 cells with TGF-beta1 addition, while ectopic DENTT expression had no significant effect on the transcription of a retinoic acid-responsive element reporter in the presence of retinoic acid or TGF-beta1. These findings suggest new possibilities for DENTT as a TGF-beta1-regulated, but not a retinoic acid-regulated member of the TTSN superfamily in primate physiology.

Differentially expressed nucleolar TGF-beta1 target (DENTT) in mouse development

Differentially expressed nucleolar TGF-beta1 target (DENTT) is a recently identified gene whose mRNA is differentially affected by TGF-beta1 in TGF-beta1-responsive human lung cancer cells and who is a new member of the TSPY/TSPY-like/SET/NAP-1 (TTSN) protein superfamily. Here, we report that mouse DENTT mRNA contains a 2031-bp open reading frame that encodes a predicted polypeptide of 677-amino acids with a relative molecular mass of 77,671 Da. The mouse and human DENTT sequences show 77% and 78% homology at the nucleotide and amino acid level, respectively. Mouse DENTT is predicted to be a nuclear protein with two nuclear localization signals (NLS), two coiled-coil regions, and a domain that shows significant identity to a region that defines the TTSN superfamily. Green fluorescent protein (GFP)-tagged full-length mouse DENTT transfected into COS-7 cells showed localization predominantly in the nucleolus. Reverse transcription-polymerase chain reaction amplification, Northern hybridization, and Western blot analyses showed expression of mouse DENTT mRNA and protein throughout mouse embryogenesis. Immunohistochemical staining analysis showed that DENTT is expressed in multiple tissues in a defined spatiotemporal pattern during mouse embryogenesis. The heart and primitive brain were the first organs of the embryo that showed immunoreactivity for the DENTT antibody by day 8 of development (E8). In the developing mouse brain, the choroid plexus was intensely stained for DENTT in all stages of development. The spinal cord and dorsal root ganglia were also positive for DENTT staining beginning in the 11-day-old embryo (E11), where homogeneous immunostaining was observed throughout the developing neurons. By day 16 of development (E16), only a small subset of the neuronal population in the spinal cord and dorsal root ganglia was positively stained for DENTT. DENTT immunoreactivity increased steadily with maturation as the differentiation of cartilage and osteoblasts proceeded and reached a maximum in the growth plate during endochondral ossification. DENTT expression was also detected in multiple rodent cell types in vitro, including mouse F9 embryonal carcinoma (EC) cells. Addition of retinoic acid or sodium butyrate to F9 EC cells showed a rapid decrease in expression of DENTT protein occurring by 1 hr that continued to decrease to almost undetectable levels after 24 hr. Cotransfection of full-length mouse DENTT expression plasmid with 3TPLux or COL7A1Luc Luciferase reporter plasmids into F9 EC cells significantly increased the level of 3TPLux reporter transcription while decreasing the level of COL7A1Luc reporter transcription, suggesting that DENTT may play multiple roles in modulating transcriptional responses. These findings suggest new roles for the TTSN superfamily during embryogenesis and differentiation.